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US 6,632,294 B2Granted
Corrosion protection of steel in ammonia/water heat pumps
AssigneeAdvanced Mechanical Technology, Inc.
InventorsFlorian B. Mansfeld, Zhaoli Sun
Life of this patent
Estimating the term…
Abstract
Corrosion of steel surfaces in a heat pump is inhibited by adding a rare earth metal salt to the heat pump's ammonia/water working fluid. In preferred embodiments, the rare earth metal salt includes cerium, and the steel surfaces are cerated to enhance the corrosion-inhibiting effects.
Claims25
A method for inhibiting corrosion of steel in an ammonia/water heat pump, comprising:
- cerating steel surfaces that will be exposed to an ammonia/water working fluid;
- and
- introducing a rare earth metal salt to an ammonia/water working fluid in a heat pump having steel surfaces exposed to the working fluid, wherein the rare earth metal includes yttrium.
A method of inhibiting both corrosion of steel surfaces and dissociation of ammonia in a heat pump having an ammonia/water working fluid comprising:
- insulating the steel surfaces with a cerated layer;
- and
- introducing a rare earth metal salt to the working fluid.
A corrosion-resistant heat pump comprising:
- a steel housing wherein the steel housing is coated with a yttrium compound;
- and
- an ammonia/water working fluid contained in the steel housing, the ammonia water/working fluid including a rare earth metal salt, wherein the rare earth metal salt includes yttrium.
Dependencies are inferred from the claim text.